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Optional variance annotations #48240

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Merged
ahejlsberg merged 13 commits into from
Mar 22, 2022
Merged

Optional variance annotations #48240

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55d0ee4
Simplify getVariancesWorker and associated logic
ahejlsberg Mar 10, 2022
24f2dcf
Accept new API baselines
ahejlsberg Mar 10, 2022
5f1c56e
Add 'in' and 'out' modififers / add modifiers to type parameters
ahejlsberg Mar 10, 2022
8dfc96f
Check variance annotations
ahejlsberg Mar 11, 2022
7793ec4
Update test runner
ahejlsberg Mar 11, 2022
8e67c07
Accept new API baselines
ahejlsberg Mar 11, 2022
a77735d
Allow variance annotations only on certain type parameters
ahejlsberg Mar 11, 2022
aa6933f
Add deprecated implementation of createTypeParameterDeclaration
ahejlsberg Mar 12, 2022
e95f4af
Accept new API baselines
ahejlsberg Mar 12, 2022
05ad13a
Report variance markers as 'sub-XXX' and 'super-XXX'
ahejlsberg Mar 12, 2022
3799524
Add tests
ahejlsberg Mar 12, 2022
33b1148
Merge branch 'main' into varianceAnnotations
ahejlsberg Mar 18, 2022
15e8d0d
Accept new baselines
ahejlsberg Mar 18, 2022
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Report variance markers as 'sub-XXX' and 'super-XXX'
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@ahejlsberg
ahejlsberg committed Mar 12, 2022
commit 05ad13a19539d28587f4d37f00edc57158c0b7fc
15 changes: 11 additions & 4 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -347,6 +347,7 @@ namespace ts {
let instantiationDepth = 0;
let inlineLevel = 0;
let currentNode: Node | undefined;
let varianceTypeParameter: TypeParameter | undefined;

const emptySymbols = createSymbolTable();
const arrayVariances = [VarianceFlags.Covariant];
Expand Down Expand Up @@ -4986,9 +4987,12 @@ namespace ts {
return factory.createTypeReferenceNode(factory.createIdentifier(idText(name)), /*typeArguments*/ undefined);
}
// Ignore constraint/default when creating a usage (as opposed to declaration) of a type parameter.
return type.symbol
? symbolToTypeNode(type.symbol, context, SymbolFlags.Type)
: factory.createTypeReferenceNode(factory.createIdentifier(type === markerSuperType ? "Super" : type === markerSubType ? "Sub" : "?"), /*typeArguments*/ undefined);
if (type.symbol) {
return symbolToTypeNode(type.symbol, context, SymbolFlags.Type);
}
const name = (type === markerSuperType || type === markerSubType) && varianceTypeParameter && varianceTypeParameter.symbol ?
(type === markerSubType ? "sub-" : "super-") + symbolName(varianceTypeParameter.symbol) : "?";
return factory.createTypeReferenceNode(factory.createIdentifier(name), /*typeArguments*/ undefined);
}
if (type.flags & TypeFlags.Union && (type as UnionType).origin) {
type = (type as UnionType).origin!;
Expand Down Expand Up @@ -18391,7 +18395,7 @@ namespace ts {
generalizedSourceType = getTypeNameForErrorDisplay(generalizedSource);
}

if (target.flags & TypeFlags.TypeParameter) {
if (target.flags & TypeFlags.TypeParameter && target !== markerSuperType && target !== markerSubType) {
const constraint = getBaseConstraintOfType(target);
let needsOriginalSource;
if (constraint && (isTypeAssignableTo(generalizedSource, constraint) || (needsOriginalSource = isTypeAssignableTo(source, constraint)))) {
Expand Down Expand Up @@ -34682,7 +34686,10 @@ namespace ts {
const symbol = getSymbolOfNode(node.parent);
const source = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSubType : markerSuperType);
const target = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSuperType : markerSubType);
const saveVarianceTypeParameter = typeParameter;
varianceTypeParameter = typeParameter;
checkTypeAssignableTo(source, target, node, Diagnostics.Type_0_is_not_assignable_to_type_1_as_implied_by_variance_annotation);
varianceTypeParameter = saveVarianceTypeParameter;
}
}
if (produceDiagnostics) {
Expand Down